Antioxidant Effects Of Piceatannol On Intestinal And Hepatic Damage Of Weaned Piglets Under The Conditions Of Oxidative Stress

Oxidative stress refers to the abnormal accumulation of reactive oxygen species(ROS)and reactive nitrogen species(RNS)in cells when they are unable to be clear timely due to the stimulation of internal and external environment.Oxidative stress can result in the imbalance of cellular homeostasis,the oxidative damage in tissues and organs,and the reduction in animal production performance and the quality of their products.Piceatannol(PIC)is a plant polyphenol with a wide range of sources,which has been widely concerned because of its biological activities including antioxidant and anti inflammation.This experiment was aimed to investigate the antioxidant protective potential of PIC to improve intestinal and hepatic damage of piglets under the conditions of oxidative stress induced by diquat(DQ),which may help to provide some clues for the application of PIC in the animal production.Trial 1 was conducted to investigate the effects of PIC on growth performance and plasma biochemical indexes of weaned piglets under the conditions of oxidative stress.A total of 54 male piglets(Duroc ×[Landrace × Yorkshire])were selected and randomly divided into three groups(each treatment group contained six replicates with three piglets per replicate).Piglets in the CS and CD groups were orally administered a vehicle solution contained 0.5%carboxymethyl cellulose sodium,while piglets in the PD group were treated with PIC at a dosage of 80 mg per kg of body weight.At the 24 h before slaughter,the CD and PD piglets were challenged with DQ at a dosage of 10 mg per kg of body weight,while the CS piglets were treated with an equal sterile saline.The feeding trial lasted for 8 days.The results showed that:(1)there was no significant difference in ADFI,ADG,or FE between the groups from 28 to 35 days of age(P>0.05).(2)Compared with the CS group,the body weight of piglets in the CD group was significantly decreased after the injection of DQ,the activity of plasma T-AOC was significantly decreased,whereas the the activities of ALT,AST,γ-GT,and DAO and the contents of T-BIL and MDA were significantly increased in plasma(P<0.05);compared with the CD group,the decrease in body weight of DQ-challenged piglets was significantly improved after PIC treatment;plasma T-AOC activity was significantly increased but the activities of ALT,AST,y-GT,DAO and the contents of T-BIL and MDA in plasma were significantly decreased in the PD group(P<0.05).Trial 2 was conducted to investigate the effects of PIC on the jejunal antioxidant capacity and villus morphology of weaned piglets under the conditions of oxidative stress.The design and method of this experiment were the same as that of the trial 1.Results showed that:(1)compared with the CS group,the activities of T-SOD and CAT and the relative expression of SOD1 were significantly decreased,but the content of MDA was significantly increased(P<0.05);compared with the CD group,the activities of T-SOD and CAT and the gene expression levels of SOD1 and HO-1 in the jejunal mucosa of piglets were significantly increased,whereas the MDA content was significantly decreased in the PD group(P<0.05).(2)Compared with the CS group,the villus height(VH)and the ratio of villus height to crypt depth(VH/CD)in the jejunal mucosa were significantly decreased,whereas the relative expression of jejunal OCLN gene was significantly decreased in the CD group(P<0.05);compared with the CD group,the jejunal VH/CD in the jejunum of PD group was significantly increased,but the relative expression of OCLN gene was significantly up-regulated(P<0.05).(3)Compared with the CS group,the apoptosis rate of jejunal epithelial cells in the CD group was significantly increased(P<0.05);in addition,the apoptosis rate of jejunal epithelial cells was significantly decreased in the PD group compared with the CD group(P<0.05).Trial 3 was conducted to investigate the effects of PIC on antioxidant capacity,morphological structure,and mitochondrial function in the liver of weaned piglets under the conditions of oxidative stress.The design and method of the present experiment were the same as that of the trial 2.Results showed that:(1)compared with the CS group,the hepatocytes of the piglets in the CD group were loosely arranged and the phenomenon of cytoplasmic vacuole was severe,accompanied with a degree of parenchymal tissue;however,the vacuolization of hepatocytes was significantly alleviated in the PD piglets.(2)The apoptosis rate of liver cells in the CD group was significantly higher than that in the CS group,while the apoptosis rate of liver cells in the PD group was significantly lower than that of the CD group(P<0.05).(3)Compared with the CS group,the BCL-2 protein expression and BAX/BCL-2 were significantly lower(P<0.05),the protein expression of BAX were increased in the CD group(P<0.05);on the contrary,the protein expression of BCL-2 and BCL-2/BAX were significantly increased,while the expression level of BAX protein was significantly decreased in the PD group compared with the CD group(P<0.05).(4)Compared with the CS group,the activities of SOD and GPx,the content of GSH,and the gene expression of NQO1,SOD1,and GSTA1 were significantly decreased,while the content of MDA was significantly increased in the CD group(P<0.05);compared with the CD group,the activities of SOD and GPx,the content of GSH,and the gene expression of NQO1,SOD1,and GSTA1 were significantly increased,while the MDA content was significantly decreased in the PD group(P<0.05).(5)Orally administering PIC increased the content of nuclear NRF2 protein and decreased the protein expression of KEAP1 in the liver of PD group.(6)Compared with the CS group,the activities of hepatic mitochondrial complex Ⅰ,Ⅱ,Ⅲ,and Ⅴ,the contents of ATP and NAD+,the gene expression of SIRT1,PGC-1α,and TFAM,the copy number of mitochondrial DNA(mtDNA),and the protein expression of SIRT1 were significantly reduced in the CD group(P<0.05);in contrast,the aboved parameters were obviously rescued by PIC treatment in the PD group compared with the CD group(P<0.05).In summary,DQ could induce obvious oxidative damage in both the jejunum and the liver of piglets,leading to the impaired jejunum morphology and barrier function excessive hepatocyte apoptosis,and hepatic mitochondrial dysfunction.Treatment with PIC improves jejunal morphology and barrier function and restores the disturbances in hepatocellular homeostasis and hepatic mitochondrial function by increasing the jejunal and hepatic antioxidant capacity in weaned piglets.